Btrfs: Fix bookend extent race v2
When dropping middle part of an extent, btrfs_drop_extents truncates the extent at first, then inserts a bookend extent. Since truncation and insertion can't be done atomically, there is a small period that the bookend extent isn't in the tree. This causes problem for functions that search the tree for file extent item. The way to fix this is lock the range of the bookend extent before truncation. Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This commit is contained in:
Yan Zheng
Chris Mason
Родитель
9036c10208
Коммит
6643558db2
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@ -3379,11 +3379,13 @@ static int noinline relocate_data_extent(struct inode *reloc_inode,
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struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
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struct extent_map_tree *em_tree = &BTRFS_I(reloc_inode)->extent_tree;
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struct extent_map *em;
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u64 start = extent_key->objectid - offset;
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u64 end = start + extent_key->offset - 1;
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em = alloc_extent_map(GFP_NOFS);
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BUG_ON(!em || IS_ERR(em));
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em->start = extent_key->objectid - offset;
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em->start = start;
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em->len = extent_key->offset;
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em->block_len = extent_key->offset;
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em->block_start = extent_key->objectid;
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@ -3391,7 +3393,7 @@ static int noinline relocate_data_extent(struct inode *reloc_inode,
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set_bit(EXTENT_FLAG_PINNED, &em->flags);
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/* setup extent map to cheat btrfs_readpage */
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mutex_lock(&BTRFS_I(reloc_inode)->extent_mutex);
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lock_extent(&BTRFS_I(reloc_inode)->io_tree, start, end, GFP_NOFS);
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while (1) {
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int ret;
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spin_lock(&em_tree->lock);
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@ -3401,13 +3403,11 @@ static int noinline relocate_data_extent(struct inode *reloc_inode,
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free_extent_map(em);
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break;
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}
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btrfs_drop_extent_cache(reloc_inode, em->start,
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em->start + em->len - 1, 0);
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btrfs_drop_extent_cache(reloc_inode, start, end, 0);
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}
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mutex_unlock(&BTRFS_I(reloc_inode)->extent_mutex);
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unlock_extent(&BTRFS_I(reloc_inode)->io_tree, start, end, GFP_NOFS);
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return relocate_inode_pages(reloc_inode, extent_key->objectid - offset,
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extent_key->offset);
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return relocate_inode_pages(reloc_inode, start, extent_key->offset);
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}
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struct btrfs_ref_path {
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@ -3831,7 +3831,6 @@ next:
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* the file extent item was modified by someone
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* before the extent got locked.
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*/
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mutex_unlock(&BTRFS_I(inode)->extent_mutex);
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unlock_extent(&BTRFS_I(inode)->io_tree, lock_start,
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lock_end, GFP_NOFS);
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extent_locked = 0;
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@ -3896,8 +3895,12 @@ next:
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lock_start = key.offset;
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lock_end = lock_start + num_bytes - 1;
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} else {
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BUG_ON(lock_start != key.offset);
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BUG_ON(lock_end - lock_start + 1 < num_bytes);
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if (lock_start > key.offset ||
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lock_end + 1 < key.offset + num_bytes) {
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unlock_extent(&BTRFS_I(inode)->io_tree,
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lock_start, lock_end, GFP_NOFS);
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extent_locked = 0;
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}
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}
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if (!inode) {
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@ -3951,7 +3954,6 @@ next:
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if (ordered)
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btrfs_put_ordered_extent(ordered);
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mutex_lock(&BTRFS_I(inode)->extent_mutex);
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extent_locked = 1;
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continue;
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}
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@ -4073,7 +4075,6 @@ next:
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}
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if (extent_locked) {
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mutex_unlock(&BTRFS_I(inode)->extent_mutex);
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unlock_extent(&BTRFS_I(inode)->io_tree, lock_start,
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lock_end, GFP_NOFS);
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extent_locked = 0;
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@ -4091,7 +4092,6 @@ out:
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if (inode) {
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mutex_unlock(&inode->i_mutex);
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if (extent_locked) {
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mutex_unlock(&BTRFS_I(inode)->extent_mutex);
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unlock_extent(&BTRFS_I(inode)->io_tree, lock_start,
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lock_end, GFP_NOFS);
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}
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@ -4180,10 +4180,8 @@ static int noinline invalidate_extent_cache(struct btrfs_root *root,
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lock_extent(&BTRFS_I(inode)->io_tree, key.offset,
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key.offset + num_bytes - 1, GFP_NOFS);
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mutex_lock(&BTRFS_I(inode)->extent_mutex);
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btrfs_drop_extent_cache(inode, key.offset,
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key.offset + num_bytes - 1, 1);
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mutex_unlock(&BTRFS_I(inode)->extent_mutex);
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unlock_extent(&BTRFS_I(inode)->io_tree, key.offset,
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key.offset + num_bytes - 1, GFP_NOFS);
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cond_resched();
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@ -946,8 +946,12 @@ int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end,
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err = set_extent_bit(tree, start, end, EXTENT_LOCKED, 1,
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&failed_start, mask);
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if (err == -EEXIST)
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if (err == -EEXIST) {
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if (failed_start > start)
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clear_extent_bit(tree, start, failed_start - 1,
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EXTENT_LOCKED, 1, 0, mask);
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return 0;
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}
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return 1;
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}
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EXPORT_SYMBOL(try_lock_extent);
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@ -364,6 +364,7 @@ int noinline btrfs_drop_extents(struct btrfs_trans_handle *trans,
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u64 start, u64 end, u64 inline_limit, u64 *hint_byte)
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{
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u64 extent_end = 0;
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u64 locked_end = end;
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u64 search_start = start;
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u64 leaf_start;
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u64 ram_bytes = 0;
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@ -479,12 +480,6 @@ next_slot:
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goto next_slot;
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}
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if (found_inline) {
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u64 mask = root->sectorsize - 1;
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search_start = (extent_end + mask) & ~mask;
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} else
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search_start = extent_end;
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if (end <= extent_end && start >= key.offset && found_inline)
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*hint_byte = EXTENT_MAP_INLINE;
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@ -501,6 +496,26 @@ next_slot:
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if (found_inline && start <= key.offset)
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keep = 1;
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}
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if (bookend && found_extent && locked_end < extent_end) {
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ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
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locked_end, extent_end - 1, GFP_NOFS);
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if (!ret) {
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btrfs_release_path(root, path);
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lock_extent(&BTRFS_I(inode)->io_tree,
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locked_end, extent_end - 1, GFP_NOFS);
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locked_end = extent_end;
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continue;
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}
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locked_end = extent_end;
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}
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if (found_inline) {
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u64 mask = root->sectorsize - 1;
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search_start = (extent_end + mask) & ~mask;
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} else
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search_start = extent_end;
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/* truncate existing extent */
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if (start > key.offset) {
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u64 new_num;
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@ -638,6 +653,10 @@ next_slot:
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}
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out:
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btrfs_free_path(path);
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if (locked_end > end) {
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unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
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GFP_NOFS);
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}
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btrfs_check_file(root, inode);
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return ret;
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}
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@ -246,7 +246,6 @@ static int cow_file_range_inline(struct btrfs_trans_handle *trans,
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return 1;
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}
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mutex_lock(&BTRFS_I(inode)->extent_mutex);
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ret = btrfs_drop_extents(trans, root, inode, start,
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aligned_end, aligned_end, &hint_byte);
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BUG_ON(ret);
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@ -258,7 +257,6 @@ static int cow_file_range_inline(struct btrfs_trans_handle *trans,
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compressed_pages);
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BUG_ON(ret);
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btrfs_drop_extent_cache(inode, start, aligned_end, 0);
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mutex_unlock(&BTRFS_I(inode)->extent_mutex);
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return 0;
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}
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@ -437,9 +435,7 @@ again:
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BUG_ON(disk_num_bytes >
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btrfs_super_total_bytes(&root->fs_info->super_copy));
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mutex_lock(&BTRFS_I(inode)->extent_mutex);
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btrfs_drop_extent_cache(inode, start, start + num_bytes - 1, 0);
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mutex_unlock(&BTRFS_I(inode)->extent_mutex);
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while(disk_num_bytes > 0) {
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unsigned long min_bytes;
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@ -477,8 +473,6 @@ again:
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em->block_start = ins.objectid;
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em->block_len = ins.offset;
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em->bdev = root->fs_info->fs_devices->latest_bdev;
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mutex_lock(&BTRFS_I(inode)->extent_mutex);
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set_bit(EXTENT_FLAG_PINNED, &em->flags);
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if (will_compress)
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@ -495,7 +489,6 @@ again:
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btrfs_drop_extent_cache(inode, start,
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start + ram_size - 1, 0);
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}
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mutex_unlock(&BTRFS_I(inode)->extent_mutex);
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cur_alloc_size = ins.offset;
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ret = btrfs_add_ordered_extent(inode, start, ins.objectid,
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@ -1016,8 +1009,6 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
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INIT_LIST_HEAD(&list);
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mutex_lock(&BTRFS_I(inode)->extent_mutex);
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ret = btrfs_drop_extents(trans, root, inode,
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ordered_extent->file_offset,
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ordered_extent->file_offset +
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@ -1059,7 +1050,6 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
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btrfs_drop_extent_cache(inode, ordered_extent->file_offset,
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ordered_extent->file_offset +
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ordered_extent->len - 1, 0);
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mutex_unlock(&BTRFS_I(inode)->extent_mutex);
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ins.objectid = ordered_extent->start;
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ins.offset = ordered_extent->disk_len;
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